Poco test using clock_gettime() and gettimeofday()
Mon Nov 17 18:53:00 GMT 2014
On 17/11/14 12:41, Corinna Vinschen wrote:
> On Nov 15 16:56, David Stacey wrote:
>> I'm not convinced that the test is valid. Poco seems to be making
>> assumptions about clock_gettime() and gettimeofday() that simply aren't
>> guaranteed to hold - but obviously do in Fedora at least. For instance, the
>> test must be assuming that either the accuracy of the two routines is
>> identical, or be making assumptions about rounding in the less accurate
>> I think it would be better to patch the test so that it uses clock_gettime()
>> exclusively (and not gettimeofday() at all), and then this problem will
>> disappear. But I thought I would submit it here to see what you thought
>> before raising a ticket with the Poco developers.
>> What do you think?
> Same as you. One problem is that CLOCK_REALTIME (which is the one used
> by gettimeofday) is not monotonic by definition, see for instance the
> Linux man page:
> This clock is affected by discontinuous jumps in the system time
> (e.g., if the system administrator manually changes the clock), and by
> the incremental adjustments performed by adjtime(3) and NTP.
> The second problem, and that's the one affecting this testcase mostly,
> is the accuracy of the timer (see clock_getres function).
Thank you for confirming my suspicions. I'll patch the test and roll a
poco-1.4.7 later in the week. I'll also raise a ticket and get this
Thanks once again,
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